David Moyes confirmed on Monday morning that United were still pursuing the Spain international, amid reports that the Premier League champions had submitted a £30m offer.
United have already had a £25m bid rejected for the former-Arsenal star, but the report claims Barcelona have now turned down this second improved offer.
After missing out on ex-Barcelona starlet Thiago Alcantara, Moyes turned his attention to Fabregas. The club is desperate to strengthen their central midfield, and Fabregas has been identified as their top target.
In a transfer market short on world-class talent at reasonable prices, United felt they could bring Barcelona to the negotiating table over Fabregas.
The 26-year-old midfielder has failed to establish himself as a first-team regular at the Nou Camp amid fierce competition for places.
He's spoken in the past of his desire to see out his contract at his boyhood club, but the prospect of first-team football at Old Trafford could prove alluring - especially in a World Cup year.
But it seems Barcelona are unwilling to part with the talented playmaker.